Purpose :
Dopamine plays a critical role in the retinal dark-light switch during the night-day transition. Yet, the way in which dopamine release is regulated in scotopic and mesopic lighting conditions remains unknown. Here we examine rod-mediated responses of dopaminergic amacrine cells (DACs) at a wide range of light intensities in order to understand the contribution of rods to the regulation of DAC activity.

Methods :
A transgenic mouse model in which DACs are genetically labeled with red fluorescent protein was used. The cone phototransduction pathway was genetically eliminated in this model. Possible inputs from intrinsically photosensitive retinal ganglion cells to DACs were blocked by TTX (Prigge and Zhang, 2015). In most experiments, fluorescent labeling was visualized using a multi-photon laser to minimize photopigment bleaching.